U.S. President Donald Trump and U.S. Secretary of Defense Pete Heges [Reuters=Yonhap News]

Reports have emerged that top aides in the U.S. administration persuaded President Donald Trump that civilian infrastructure in Iran are "legitimate" military targets.

Close associates, including Secretary of Defense Pete Heges, strongly advocated for attacking power plants and bridges within Iran, and President Trump reportedly agreed.

The U.S. daily Wall Street Journal (WSJ) reported on the 4th (local time) that Secretary Heges directly briefed President Trump on the legal basis for striking civilian targets.

According to sources, Secretary Heges advised that roads could be included in the scope of attack, citing the Iranian military's potential use of the road network for transporting missile or drone components.

Another White House official reportedly briefed that attacking power plants would incite public unrest and hinder Iran's nuclear development, and therefore, power plants should be considered legitimate military targets.

Indeed, following President Trump's announcement on the 1st to "return Iran to the Stone Age," the U.S. military carried out an airstrike destroying a large bridge near Tehran, Iran, and has declared that it would also target power plants if Iran does not reach an agreement based on U.S. demands.

In addition to roads and power plants, the U.S. and Israel conducted airstrikes on petrochemical complexes in Mahshahr and Bandar-e Imam, Iran, this morning, resulting in 5 deaths and 170 injuries.

However, according to the WSJ, current and former military officials warn that attacking an adversary's infrastructure solely to exert pressure is illegal.

The U.S. has attacked bridges and energy infrastructure in past wars in the Middle East, but the newspaper noted that such attacks were limited to cases where the military advantage was clear and did not cause excessive civilian casualties.

U.S. attacks on Iranian civilian infrastructure also carry the risk of retaliatory attacks on energy facilities in the Gulf region.

The WSJ reported that Gulf nations conveyed these concerns to the U.S. after President Trump warned of attacks on Iranian power plants.

Iran has strongly condemned the U.S. attacks on its civilian facilities.

According to Iran's state news agency IRNA, Iran's Ambassador to the UN, Amir Saeed Iravani, claimed in a letter to the UN that the attacks on civilian facilities, including bridges and petrochemical complexes in Iran, were "war crimes" and "blatant acts of state terrorism."

Iran's Deputy Foreign Minister Abbas Araghchi also warned in a separate letter to the UN Secretary-General and the Security Council that "attacks on Iran's nuclear facilities are illegal and violate international law, and could lead to serious humanitarian and environmental consequences," according to Iran's semi-official Mehr News Agency.